1. Field of the Invention:
This invention relates to systems and configurations for filtering particulates from hot gaseous mediums.
2. Description of the Prior Art:
Among the many processes being considered for generation of synthetic fuels is gasification of hydrocarbonaceous materials such as coal. Such processes produce a combustible product gas which can be burned for industrial or other use. The gaseous product can also be used in so-called combined cycle plants, where the generated gas is directly used in a gas turbine. However, such plants require a manner in which to remove small particulates of coal, carbon and ash, of less than 5 microns, from the gaseous product, prior to entry into the turbine in order to prevent degradation of the turbine blading.
Many other existing and contemplated uses for carbonaceous materials are being considered. Pressurized, fluidized bed combustion processes, for example, combust coal and transfer heat to a fluid, such as water or air, flowing through tubes passing through the containing vessel. The combustion products, which can be expanded through turbines, will also have to be filtered from this process, and in addition will include particulate absorbent such as limestone or dolomite dust.
The product discharged from the various systems is not only abrasive, but also is discharged at a high temperature. For example, fluidized bed combustion processes discharge raw product gas at temperatures in the range of 1200.degree. to 1800.degree. F., providing imitations on filter materials. Conventional devices for hot gases, such as cyclones, are useful for removing larger particulates, but are of limited value in removal of particulates smaller than 5 to 10 microns. More advanced concepts in hot gas cleaning, for example, a granular bed filter design, have shown promise for fine particulate removal, but rely on large and cumbersome equipment.
It is desirable to provide filtration systems which meet the stringent requirements imposed by high temperature gases containing fine particulates.